1. Field of the Invention
The invention relates to a method for producing perforated or partially perforated stencils which have on their upper side a relief with a multiplicity of openings, the contours of which correspond to a desired pattern, and relates to stencils of this type.
2. Brief Discussion of the Related Art
EP 1 884 582 B1 already discloses a method for producing a stencil or a screen in which a screen body is first provided, having a multiplicity of through-openings which extend from the upper side to the rear side. In order to form a relief in the upper side, lower-lying regions or openings are removed by a chemical process by etching or by means of laser radiation in accordance with a desired pattern. The screen body that is provided with a multiplicity of through-openings may in principle consist here of non-metallic materials, such as for example plastic, ceramic, natural resin or lacquer materials that are suitable for forming stable sheet-like elements, composite materials or a combination thereof, but only the production of screen bodies made of metal, such as nickel, copper or aluminum, or alloys thereof, is described in detail here.
US 2008/0193790 A1 discloses a screen drum which serves for producing nonwovens by means of a liquid jet bonding process. The screen drum has here on its upper side, to which the fibrous material is applied, lower-lying regions or openings, the contours of which correspond to a desired pattern. The screen drum is galvanically produced in two phases. In a first phase, a carrier screen with a multiplicity of through-openings is created. After achieving the desired thickness, then, in a second phase, the thickness of the screen drum is further increased only where raised regions are intended, so that lower-lying regions or openings of a relief occur. The walls of the openings of the relief are slightly inclined outwardly.
DE 10 2007 059 794 A1 discloses a method for producing a screen printing stencil in which recesses are machined out of a metallic carrier substrate from the later scraper side, in order to create a carrier network. On the later substrate side, the structure to be printed is then machined in the form of further recesses, so that openings for the pasty screening material form at the places at which the fronts of the recesses on both sides meet in the stencil body. The production of the stencil is performed here by micro-etching or laser ablation.
However, production methods of this type only permit limited relief heights. In the case of galvanic stencils, it is also disadvantageous that the through-openings become increasingly narrow with increasing thickness, which further restricts relief heights.
Against this background, the invention is based on the object of providing a further method for producing stencils and improved stencils that permits greater relief heights and consequently greater freedom of design for patterns to be applied.